This invention relates to ink jet printheads. More particularly, this invention relates to a nozzle arrangement for an ink jet printhead which includes a refill actuator.
The Applicant has invented an ink jet printhead that is capable of generating text and images at a resolution of up to 1600 dpi.
In order to achieve this, the Applicant has made extensive use of micro electromechanical systems technology. In particular, the Applicant has developed integrated circuit fabrication techniques suitable for the manufacture of such printheads.
The printheads developed by the Applicant can include up to 84000 nozzle arrangements. Each nozzle arrangement has at least one moving component which serves to eject ink from a nozzle chamber. These components usually either act directly on the ink or act on a closure which serves to permit or inhibit the ejection of ink from the nozzle chamber.
The printheads are manufactured in accordance with an integrated circuit fabrication technique. It follows that the moving components are microscopically dimensioned. This is necessary, given the large number of nozzle arrangements per printhead. In order for printheads incorporating such nozzle arrangements to operate efficiently, not only must the moving components be capable of operating at a relatively high speed, it is also necessary that the nozzle chamber be refilled at a speed which is complementary to that of the components.
In use, once a moving component has been displaced within a nozzle chamber to eject ink from the nozzle chamber, that moving component usually returns to an original condition to be ready for again ejecting ink from the nozzle chamber. It is important that, when the moving components return to their original condition, the nozzle chamber is again rapidly filled with ink. This will ensure that, after it has returned to its original condition, the nozzle chamber is filled with ink so that the nozzle arrangement can operate accurately and correctly if activated immediately after it has returned to its original condition.
The present invention has been conceived by the Applicant in order to address the problem of achieving a high refilling rate of the nozzle chamber.
According to a first aspect of the invention, there is provided a nozzle arrangement for an ink jet printhead, the nozzle arrangement comprising
a substrate;
nozzle chamber walls arranged on the substrate to define a nozzle chamber;
at least one ejection actuator that is operatively positioned with respect to the nozzle chamber, the, or each, ejection actuator being displaceable between an inoperative condition and an operative condition to eject ink from the nozzle chamber and including an actuating mechanism to facilitate such displacement; and
at least one refilling actuator that is operatively positioned with respect to the nozzle chamber, the, or each, refilling actuator being displaceable between an inoperative condition and an operative condition to direct ink into a zone in which the ink can be acted on by the ejection actuator, subsequent to the ejection of ink from the nozzle chamber, and also including an actuating mechanism to facilitate such displacement.
According to a second aspect of the invention, there is provided an ink jet printhead which comprises
a substrate; and
a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising
nozzle chamber walls arranged on the substrate to define a nozzle chamber;
at least one ejection actuator that is operatively positioned with respect to the nozzle chamber, the, or each, ejection actuator being displaceable between an inoperative condition and an operative condition to eject ink from the nozzle chamber and including an actuating mechanism to facilitate such displacement; and
at least one refilling actuator that is operatively positioned with respect to the nozzle chamber, the, or each, refilling actuator being displaceable between an inoperative condition and an operative condition to direct ink into a zone in which the ink can be acted on by the ejection actuator, subsequent to the ejection of ink from the nozzle chamber, and also including an actuating mechanism to facilitate such displacement.
According to a third aspect of the invention, there is provided a method of ejecting ink from a nozzle arrangement of an ink jet printhead, the nozzle arrangement including a substrate, nozzle chamber walls arranged on the substrate to define a nozzle chamber, at least one ejection actuator that is displaceable between an inoperative and an operative condition to facilitate the ejection of ink from the nozzle chamber and at least one refill actuator that is displaceable between an operative condition and an inoperative condition to direct ink into a zone in which the ink can be acted upon by the ejection actuator, the method including the steps of:
supplying the nozzle chamber with ink;
activating the, or each, ejection actuator so that ink is ejected from the nozzle chamber; and
activating the, or each, refill actuator at a predetermined time after activation of the, or each, ejection actuator so that ink is directed into said zone to be acted upon again by the, or each, ejection actuator, if required.